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Message-Id: <20240320-kpageflags-svetly-v3-1-b6725843bfa7@memverge.com>
Date: Wed, 20 Mar 2024 10:28:09 -0700
From: Svetly Todorov <svetly.todorov@...verge.com>
To: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org, gregory.price@...verge.com,
willy@...radead.org, wangkefeng.wang@...wei.com, akpm@...ux-foundation.org,
david@...hat.com, vbabka@...e.cz, naoya.horiguchi@...ux.dev,
Svetly Todorov <svetly.todorov@...verge.com>
Subject: [PATCH v3] kpageflags: respect folio head-page flag placement
---
Page flags are now stored per-folio. Change kpageflags to report these
per-folio flags where appropriate.
Most folio flags are set on the head page, i.e. *folio_flag(page, 0).
Only three are set on the second page -- PG_has_hwpoisoned, PG_large_rmappable,
and PG_hugetlb. kpageflags doesn't report the first two, and the PG_hugetlb
check is handled by calls to PageHuge/PageTransCompound(), so no code changes
are required for these flags.
mm/memory-failure.c applies PG_HWPoison via SetPageHWPoison(page).
This call falls through to the SetPage##uname macro in
include/linux/page-flags.h, which sets the corresponding PG_##lname bit
on the given page struct. Therefore KPF_HWPOISON must come from page->flags.
arch/xtensa/mm/cache.c tests and sets the PG_arch1 bit in both
folio->flags and page->flags. So both sources are OR'd into KPF_ARCH.
As for arch2 and arch3, Kefeng Wang reported that they appear only as
arm64-specific aliases: namely, PG_mte_tagged and PG_mte_lock.
Both are applied to page->flags via set_bit() in arch/arm64/include/asm/mte.h.
So those must come from page->flags, too.
Signed-off-by: Svetly Todorov <svetly.todorov@...verge.com>
Suggested-by: Matthew Wilcox <willy@...radead.org>
Suggested-by: Gregory Price <gregory.price@...verge.com>
Suggested-by: Kefeng Wang <wangkefeng.wang@...wei.com>
Link: https://lore.kernel.org/all/20231030180005.2046-1-gregory.price@memverge.com/
Link: https://80x24.org/lore/linux-mm/20231110033324.2455523-4-wangkefeng.wang@huawei.com/
Link: https://80x24.org/lore/linux-mm/438ba640-c205-4034-886e-6a7231f3d210@huawei.com/
---
fs/proc/page.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 195b077c0fac..290470819fa2 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -110,6 +110,7 @@ static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
u64 stable_page_flags(struct page *page)
{
u64 k;
+ u64 p;
u64 u;
/*
@@ -119,7 +120,8 @@ u64 stable_page_flags(struct page *page)
if (!page)
return 1 << KPF_NOPAGE;
- k = page->flags;
+ k = *folio_flags(page, 0);
+ p = page->flags;
u = 0;
/*
@@ -205,7 +207,7 @@ u64 stable_page_flags(struct page *page)
u |= kpf_copy_bit(k, KPF_MLOCKED, PG_mlocked);
#ifdef CONFIG_MEMORY_FAILURE
- u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison);
+ u |= kpf_copy_bit(p, KPF_HWPOISON, PG_hwpoison);
#endif
#ifdef CONFIG_ARCH_USES_PG_UNCACHED
@@ -216,11 +218,14 @@ u64 stable_page_flags(struct page *page)
u |= kpf_copy_bit(k, KPF_MAPPEDTODISK, PG_mappedtodisk);
u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private);
u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2);
+ u |= kpf_copy_bit(p, KPF_PRIVATE, PG_private);
+ u |= kpf_copy_bit(p, KPF_PRIVATE_2, PG_private_2);
u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1);
+ u |= kpf_copy_bit(p, KPF_ARCH, PG_arch_1);
#ifdef CONFIG_ARCH_USES_PG_ARCH_X
- u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2);
- u |= kpf_copy_bit(k, KPF_ARCH_3, PG_arch_3);
+ u |= kpf_copy_bit(p, KPF_ARCH_2, PG_arch_2);
+ u |= kpf_copy_bit(p, KPF_ARCH_3, PG_arch_3);
#endif
return u;
---
base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
change-id: 20240319-kpageflags-svetly-9faa11b17022
Best regards,
--
Svetly Todorov <svetly.todorov@...verge.com>
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